Fluid operated brake system



Jan. l0, 1950 H. TREVASKlS FLUID OPERATED BRAKE SYSTEM Filed May 2. 1947 Patented Jan. 10, 1950 FLUID OPERATED BRAKE SYSTEM nem wuunm 'r1-mms. sounuu, Birmingham, England, assignor to Dunlop Rubber Company Limited, London County, England, a British corporation Application May 2, 1947, Serial No. 745,479 In Great Britain May 20, 1946 (CL 18S-152) 4Claims.

l My invention relates to fluid operated brake systems for aircraft provided with duplicate sets ofcontrols for the iiuid transmission lines, one pair of duplicate controls operating the brakes on one side of the aircraft'and the other pair of duplicate controls operating the brakes on the through a line I1 and branches I l to the control umts III and II, and similarly through a line I9 and branches to the control umts Il and Il.

The pressure fluid supplied from the main i6 to the control units I0 andl I4 may be admitted or released through supply pipes 2i and 22 to one unit 23 oi a master control unit and thence through a connecting line or delivery pipe 24 to or from the brake I2 or to a suitable mechanism to control the admission of iluid to the brakes.

Similarly fluid supplied from the main I6 may be admitted or released through the supply pipes 25 and 26 to a second unit 21 of the master line connected to the other control. With brake systems of this type, however, it is possible for one pilot to release the brakes inadvertently after they have been applied by the other pilot for parking purposes.

The present invention providesl means which renders the pairs of duplicate controls inoperative when the brakes are in a parking condition.

According to the invention duid-operated brake systems of the above type are provided with a master control device adapted to place both the valve units simultaneously either in an operative position in which either pilot can release iluid pressure through the valve units for application of the brakes or in an inoperative position in which the iiuid transmission lines for both pairs of controls to the valve units are sealed oir.

'Ihe various features of my invention are illustrated by way of example in the accompanying drawings in which Fig. 1 is a' diagrammatic representation of a i'iuid operated aircraft braking system embodylng my invention;

Fig. 2 is a sectional view on a larger scale of a master control device to place the braking units simultaneously in operative or in inoperative position and showing the parts in position to permit operation of the brakes;

Fig. 3 is a view similar to that of Fig. 2 but showing the parts'in parking or inoperative position.

In the embodiment' shown in Fig. 1 the brake system shows a pair of control units I0 and II at one station for operation by one pilot to control respectively the brakes I2 and I3 on opposite sides of the plane or aircraft, and a second pair of control units I l and I5 which may independently control the operation of the brakes I2 and I3.

control and thence through a supply pipe 28 to or from the brake apparatus I3. Each oi' the brake apparatus I2 and I3 is, therefore, under the independently acting controls III and II and I4 and I5 respectivelythrough the master control units 23 and 21.` These units may, however, be set in parking' position in which brake iluid cannot be released from the brakes.

'I'he construction and operation of the master control unit 23 is shown in Figs. 2 and 3, it being understood that control unit 21 is the same in all respects. This unit comprises a box or chamber having a pair of spaced cylindrical bores 2l and 30, the upper ends of which are closed respectively by screw plug connectors 3l and 32 having passages for connection tothe supply pipes 2|, 22, respectively.

In the cylindrical bores 29 and 20 are valve pistons 33 and 34 which `may move upwardly to close against valveseats formed on the bottoms of the connecting plugs BI and 32 respectively, or downwardly toward open position.

The chamber or box 23 is also provided with an outlet connector plug 35 which connects to the delivery pipe 2l. Y

The valve pistons 33 and 2| are pivotally connected to the ends of a iloating lever 38 which is secured at a point mid way of the valve pistons 23 and 34 to a bracket 31 movable vertically by means of a link 3B. This link passes through a fluid-tight packing gland 39 in the cover of the chamber and is connected at its upper end in an articulated connection to a cross-rod 40 4which also connects a similar link of the second controll unit 21.

As shown in Fig. 2 the link I8 is normally pushed downwardly by a spring 4I conned between the bracket 31 and a recess in the top wall or cover of the chamber 22 so as to hold one or both of the valve pistons Il and ll in open position and thus to permit free passage of iluid from Pressure duid is supplied from a main I6 55 the delivery pipe 2l to or from either of the pipes 2| and 22; When fluid is forced through the connector l2 and bore I0 it forces the piston valve downwardly out of the bore and tilts the lever to the position shown in Fig. 2 closing valve 33 and, conversely, when valve 33 is forced downwardly to open position the lever 38 is tilted to close valve N. This is the normal position of the apparatus when the control units are not in parking position.

When the apparatus is set for parking the connecting or cross-rod 4,0 is raised to the position shown in Fig. 3 by means of a lifting rod l2 to which it is pivotally connected at approximately its mid point and which in turn is lifted by a cable 43, one end of which is secured'to the lifting rod 42 and the other end of which is secured to a parking lever M. When this lever is' moved to the position shown in Fig. 3 it raises the lifting rod l2 and the link 38 and thereby raises the floating lever 36 until each of the piston valves 33 and M is closed tightly on the lower valve face of its respective plug 3l or I32. In this; position no fluid can be released from the delivery pipe 24, or 2 8, and the brakes once applied cannot be released until the parking lever is moved to the position of Fig. 2.

When the plane is to be parked the brakes are applied by operation of the control units I0 and l I or Il and l5 and the parking lever M' moved to the position shown in Fig. 3. The pressure uid is thereupon trapped in the brake system and cannot be released from any of the stations I0, Il, Il or.|5 until the parking lever is moved to the position shown in Fig. 2. Accordingly it is impossible to release the brakes inadvertently from their parking condition.

Having described my invention, what I claim is:

1. Fluid control brake apparatus which comprises a pair of brake applying means, two pairs of manual control units, one for each brake applying means, to control independently admission of fluid to, or its release from, said brake applying means, a master control for each brake applying means having a pair of valves, one for each of said control units, opening under fluid pressure from its respective control unit to its respective brake applying means, a lever connecting said valves to close one when the other is opened by fluid pressure, and a fulcrum for said lever movable to close both said valves.

. 2. The apparatus of claim 1 having a lever connected to the fulcrums of both said master controls and means acting on said lever betweensaid fulcrums to move said fulcrums.

3. The apparatus of claim 1 in which said master control has a cylindrical bore for each valve of said pair in said unit between its open and closed position.

4: A master control for fluid pressure operated apparatus which comprises a hollow casing having an outlet and a pair of axially parallel inlets opening into said casing, a rod-like member having one end extending into the casing, said member being equidistantly spaced between said inlets, a lever pivoted on said end, and valves, one pivotally mounted on said lever within the casing on each side of the pivot, each valve being positioned to close one of said inlets, said member being movable parallel to said inlets between a position wherein each valve is held on its respective inlet and a position wherein the lever and its associated valves are free to rock about its pivot.

HENRY WILLIAM TREVASKIS.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS 

